Summer is here, as we can easily witness by the lengthening days, rising temperatures and row upon row of sunscreen products filling store shelves. According to the American Academy of Dermatology (2010), these products are key to good skin health and preventing dangerous skin cancers since "sun exposure is the most preventable risk factor for all skin cancers, including melanoma." But in recent years studies are showing this advice to be erroneous and obsolete. In fact, the largest rise in melanoma rates has been in countries where chemical sunscreens are heavily advocated (Garland, 1992).
In 2007, Moore's Cancer Center at the University of California, San Diego demonstrated a direct connection between colorectal and breast cancer risk and serum D3 levels, showing lower incidences of these cancers among those with higher levels of Vitamin D. While a reduced cancer risk is a powerful motivator to obtain adequate levels of Vitamin D, the benefits of "the sun vitamin" extend well beyond cancer protection (read more about Vitamin D below). As much as 90% of our Vitamin D comes from sun exposure, and applying a sunscreen as low as SPF 8 can reduce vitamin D production by 95% (Higdon, 2008).
While many sources advise that 20 minutes of daily sun exposure on your face and arms will provide all the Vitamin D you need, this is not necessarily true. Adequate sun exposure will vary depending on your location and skin type. More exposure will be required the farther north you travel from the equator, and dark-skinned people will require more exposure than fair-skinned people. For Caucasians, Vitamin D production averages 20-30 minutes. If you are darker skinned, it can take three to four times that long. An hour of sun exposure on at least 40% of your body per day is not an unreasonable amount of time to spend in the sun for good health.
Regular exposure of as much skin as possible is key--it's better to have short periods of daily exposure than several hours once per week. Begin in the morning (when the chance of burning is the least) in spring and early summer to get your skin used to sun exposure. Gradually increase your time in the sun. It is virtually impossible to overdose on Vitamin D from sun exposure, since exposed skin reaches an equilibrium point where Vitamin D begins to convert to inert chemicals. However, the most important thing to remember is to avoid sunburn, since sunburn can increase the risk of basal cell carcinoma (the less fatal form of skin cancer).
While many people may be tempted to prepare for the summer sun using tanning beds, that can be a dangerous mistake. Tanning beds are designed to tan the skin deeply in a short period of time without burning, which is accomplished by minimizing the amount of UVB radiation. However, UVB is what stimulates Vitamin D production, and the burn response is the body's mechanism to prevent Vitamin D excess. Not only does high levels of UVA radiation break down Vitamin D, it i s also suspected to be associated with increased melanoma risk (melanoma is a more threatening form of skin cancer). An additional problem with tanning beds is the radiation emitted by the magnetic ballasts used to power the bulbs--often these ballasts are very close to the person in the bed, leaving them exposed to very strong magnetic fields while tanning.
While the best sunscreen is internal sunscreen from antioxidants such as blackberries, blueberries, raspberries, goji berries, spirulina, and chlorella, we all find ourselves in need of a sunscreen at one time or another. If sun exposure is not a possibility for whatever reason, or you find yourself required to spend more time outdoors than your skin can safely handle and you cannot cover up or find shade, it is better to use a sunscreen than to risk a burn. But keep in mind that not all sunscreens are created equal. The Environmental Working Group (2010) has found that 84% of sunscreens with an SPF of 15 or higher contained potentially harmful ingredients and/or provided inadequate protection. If you plan to use a sunscreen, check their database to ensure it provides the protection you require and doesn't contain harmful chemicals. http://www.ewg.org/2010sunscreen/